This invention relates to a printing apparatus, and more particularly it is concerned with improvements in or relating to an optional components mounting mechanism of a printing apparatus.
Generally, a printing apparatus has components that are optionally mounted, such as a printing sheet guide for supporting a single sheet that is inserted, a page feeder for successively feeding a set of sheets arranged continuously, etc. In a printing apparatus of the type generally referred to as an impact printer wherein printing types are struck with a hammer when printing is performed, a sound absorber or a noise silencing cover may optionally be mounted for avoiding making a noise.
Printing apparatus of the prior art have suffered, however, the disadvantage that if at least one of the sound absorber, noise silencing cover and printing sheet guide is mounted, then it is impossible to mount the page feeder. When it is necessary to mount the page feeder, it is necessary to dismount the sound absorber, noise silencing cover and printing sheet guide, and this is troublesome and makes one wonder where the removed components should be placed. To avoid this trouble, attempts have been made to produce two types of printing apparatus, one type being adapted to mount the sound absorber, noise silencing cover and printing sheet guide and the other type being intended to mount the page feeder. Also, some printing apparatus have had the page feeder and the noise silencing cover attached thereto, which became so large in size that separate printing apparatus have been produced merely for mounting the printing sheet guide. In the type of printing apparatus mounting the page feeder, one has to remove the noise silencing cover and a front cover of the printing apparatus when the ribbon and printing wheels are replaced by new ones, and one has to remove the page feeder each time the ribbon and printing wheel are replaced by new ones, depending on the type of printing apparatus. Opening and closing the noise silencing cover and front cover have tended to cause abnormal conditions to be produced in the printing apparatus in which the sheet in the process of setting might be folded or wound on the platen, making it inevitable to reinsert the sheet into the printing apparatus.
Printing apparatus adapted to mount optionally the page feeder for feeding into the printing section sheets arranged continuously in a set might be constructed such that when the page feeder is mounted, left and right side frames of the page feeder penetrate a printer cover and are brought into engagement with engaging portions in the interior. When this type of printing apparatus has no page feeder mounted thereon, the page feeder mounting portions (portions where the frames penetrate the printer cover) of the printer cover would be left open to allow the engaging portions and gears in the interior to be exposed to view. When this is the case, the operator might be tempted to put fingers into the openings or the fingers might actually be injured by mistake. In the impact type printing apparatus, sound is produced each time printing is performed, so that it is usual practice to cover the printing section with the sound absorber or noise silencing cover to avoid release of noise to the outside. However, noise might be emitted through the openings of the page feeder mounting portion unless the openings are closed.